The present invention is directed generally to laser alignment systems. It is directed in particular to a compact, portable laser alignment tool which may simultaneously indicate level, plumb, and square alignment.
A portable, rugged, inexpensive, self-leveling laser device, capable of simultaneously indicating level, plumb and square alignment would be a very useful tool for the construction and carpentry trade. There have been a number of laser alignment devices disclosed which employ lasers. None of the devices, however, include all of the desired features of portability, self leveling and the ability to provide the simultaneous indication of the three principle alignment directions, i.e. level, plumb, and square.
U.S. Pat. No. 4,448,528 discloses a helium-neon laser pendulously suspended from a gimbal attached at one end of the laser. The suspended laser is surrounded by a windshield and the whole structure is mounted on a tripod. The device relies on beams emerging from each of the two ends of the helium neon laser to define an alignment line. The laser requires an external power source, potentially limiting its use to areas where external power is available.
Laser alignment devices have also been designed with a laser diode and battery power. Battery-powered devices do not require an external power source and may be used in virtually any location. For example U.S. Pat. Nos. 4,221,483; , 4,679,937; and U.S. Pat. No. 4,912,851 discloses a variety of portable surveying tool concepts. All include a light source and at least one other optical element. Pendulous suspension of either the optical element, or elements, is used to provide a self leveling capability for the tools. For example, U.S. Pat. No. 4,912,851 discloses a battery powered tool, utilizing a visible laser diode, which is self-levelling and capable of producing alignment beams indicating level and plumb directions, albeit not simultaneously. The alignment beams are switched between the level and plumb directions by manually rotating a knob on the side of the tool. The self-levelling feature of the tool is accomplished by pendulously suspending optical elements which are used to divide and direct the alignment beams. The laser diode and collimating optics are mounted in the tool separate from the pendulously suspended optical elements. A complex tilt compensation arrangement is required to compensate for changes in relative position of the laser and collimating optics, and the pendulously suspended optical elements which occur when the tool is placed on a non-level surface. A variety of tilt compensation arrangements are described in detail U.S. Pat. No 4,912,851. It is believed that a tilt compensation mechanism effective for three principle alignment directions simultaneously may be more complex than those disclosed in U.S. Pat. No 4,912,851.
Accordingly it is an object of the present invention to provide an alignment tool which does not require a tilt-compensation mechanism.
It is another object of the present invention to provide a rugged compact laser tool for projecting alignment lines which may be used to simultaneously establish level, plumb and square alignment directions.